PCIe 2.0 allows for 5.0 GT/s and PCIe 1.x 16x allows for 2.5GT/s. Do the cards being produced today even take advantage of the full bandwith availible or is this just another ploy to get everyone to upgrade their systems?

I've seen ATI's 3870X2 in a PCIe 1.1 variant so obviously there is no fear of bottlenecking with that card. So why has nvidia made the switch to PCIe 2.0 with their latest 9 series cards?